1. Field of the Invention
This invention relates to spectrophotometers. Spectrophotometers are devices for measuring intensity of light in various parts of the spectrum and, as the term is used herein, for the purposes of this patent specification, the spectrum includes invisible as well as visible radiation.
2. Description Relative to the Prior Art
Spectrophotometers are known which direct collimated light from a sample to be spectrally analyzed, onto a diffraction grating. The diffracted light is focussed onto an array of detectors and is incident on the detectors as a spectrum. However, the spectrum is not linear, that is, the positions along a linear scale, of the components in the spectrum, are not linearly related to their wavelength. Thus, if it is desired to analyze the sample by determining the intensity of the light in each contiguous, say, 20 nm increment of the spectrum, a special detector array has to be created in which each detector has a length equal to the length, along the spectrum image, of the particular portion of the spectrum which the respective detector is intended to sense. Alternatively, each of the detectors may have the same dimension along the spectrum image and the signals derived from the detectors may be processed so that a plurality of signals is produced each being indicative of the intensity in a respective, say 20 nm, increment of the spectrum. Thus, with the prior art, if one wanted a linear spectral analysis, the problem has existed that it has been necesary either to create a special and dedicated detector array or it has been necessary to process the signals derived from the detectors to provide the desired signals.
It is an object of the present invention to overcome the problems of the prior art.